“Mr. Developer, tear down those walls,” might as well be one of the slogans for São Paulo’s ambitious new urban master plan. It prohibits gated-off buildings in some parts of the city and encourages new developments that provide street-level interaction with retail.

The effort to curb street life-killing development—especially the walled-off residential complexes common across the city—could have a lasting impact on what São Paulo’s streets look like and how its residents interact with each other.

The measures are only a small part of a recently approved 150-page plan that creates strong incentives for transit-oriented development and limits the amount of space devoted to new parking. The hotly debated plan, which took nine months to gain approval, also includes progressive regional touchstones such as land access opportunities for poor residents. Critics (aka developers) argue that the policies could very well drive up housing prices.

The hope is that the master plan could help revert a 40-year trend of fenced-off tower blocks.

Developers will in fact be encouraged to incorporate commercial, service or institutional space on ground levels in exchange for increased building area, including loosened height restrictions along transit corridors.

It might not sound like a revolution, but in São Paulo the hope is that the master plan could help revert a 40-year trend of fenced-off tower blocks. A combination of zoning laws put in place in the 1970s—which encouraged higher buildings with more setback from the curb—and growing fear of violent crime led to the ubiquitous rise in São Paulo of gated condos, enclosed areas with elaborate amenities for residents and with little connection to street life. Leisure, shopping and work areas followed a similar path. By the late 1990s, São Paulo was a “city of walls”, writes Teresa Caldeira, a professor of city and regional planning at UC Berkeley.

In a society that faced increasing violence, ramped up security measures became a worthwhile premium for many, not only the über rich. São Paulo is hardly unique: such designs are common around the developing world, more so in drastically unequal cities.

“It is a mode amply adopted by the market because buyers want security and privacy in their home,” explains Nabil Bonduki, the Paulista councilman who acted as rapporteur for the Master Plan project. Yet, “there is a strong opposition to this type of development in diverse sectors of society, such as urbanists, environmentalists, neighborhood associations and cultural movements,” he writes via e-mail.

Many São Paulo apartment buildings, like this one not far from Paulista Avenue, tend to be set back from the street and separated from the surrounding community by fences. (Ana Beatriz)

It's a classic case of individual preferences that add up to the worst general outcomes for cities, according to some experts. Though they’re meant to protect residents from violent crime, they also create a society where crime is more likely.

As Caldeira notes in Fortified Urban Enclaves: The New Urban Segregation, separated spaces often serve to deepen social inequality. People in such cities have fewer encounters across class barriers, which means “... social differences are more rigidly perceived, and proximity to people from different groups is considered dangerous, thus emphasizing inequality and distance.”

Which is what makes these new incentives to encourage street life so relevant. Creating a more permeable barrier between public and private, as happens on mixed-use commercial streets, is one of the goals of active frontage, according to Bonduki. The new São Paulo master plan takes steps to revert market trends that legitimately responded to consumer preferences, but have created negative externalities for the city at large. “We think it’s necessary to change habits and lifestyles,” says the councilman.

What remains to be seen is how consumers and developers react to the new directives. Gated buildings can still be constructed, but they’ll be much more expensive and farther away from major transit corridors.

Already, there are signs of change. A recent article inFolha de São Paulo points to a pair of local developers who are already working on mixed-use projects, with shops on the ground floor, although in São Paulo, this is still seen as a new idea. Or rather, a retro idea that appears poised to make a comeback.